The S847F says it was made at the S=Sterling Plant and the 847F is the application code for the type of Ford it was used on and how much the axle can hold.

It is also a 3.55:1 ratio limited slip 8.8" rear end.

Your date code is not right at it says it was made on the 21st day of the 14th month of 1994.

Tag decoding :

3L55 88 99H06

Second part is the axle ratio: There should be a "3L" preceding the 55 if it's a Limited Slip. If it's open, it would just say '355' .
4th is the ring gear diameter, in your case an 8.8 inch.
5,6,and 7 are the build year, month, and day, in this case, August 6th, of '99. (9=1999, H=8th month [and there is no 'I' in the sequence]) and '06' is the 6th.



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